Photographic apparatus



June 4, 1957 M. N. FAlRBANK ETAL PHOTOGRAPHIC APPARATUS Filed Jan. 12, 1954 I?! Ir ATTORNEYS United States Patent PHOTOGRAPHIC APPARATUS Murry N. Fairbank, Belmont, William J. McCune, Jr., Lincoln, Richard R. Wareham, Marblehead, and Sidney B. Whittier, Cambridge, Mass., assignors to Polaroid Corporation, Cambridge, Mass., a corporation of Beta ware Application January 12, 1954, Serial No. 493,574

11 Claims. (Cl. 95-13) This invention relates to photography and more particularly to novel photographic devices.

The invention concerns a photographic device of the type capable of exposing and, immediately thereafter, processing successive frames of a photosensitive strip by spreading on the surface thereof the liquid content of a rupturable container, the liquid of the container being preferably spread between the photosensitive strip and another strip. The layer of processing liquid may be formed, for example, by superposing the srtips with a rupturable container therebetween and advancing the superposed strips between a pair of pressure-applying members. The second strip may carry one or more of the processing reagents in a condition to be dissolved in a layer of processing liquid or it may serve as an imagereceptive strip in which a visible print of a latent image in the photosensitive strip may be produced. The photosensitive strip may include a silver halide layer, the second strip may include a silver precipitating layer and the processing composition may include a developer of a silver halide solvent and an alkali. In the presence of this layer of processing composition, a latent image in the frame is reduced to silver and a soluble silver complex from unreduced silver halide is formed, is transferred by imbibition to the area and there is reduced to silver to produce a positive image. Photographic material generally useful in the foregoing processes are described in detail in Patent No. 2,543,181, issued to Edwin H. Land on February 27, 1951, for Photographic Product Comprising a Rupturable Container Carrying a Photographic Processing Liquid.

The device herein disclosed is of the type adapted to expose a frame of a photosensitive strip, for example motion picture film, to produce a latent image in said frame and, almost immediately thereafter, process said frame to form a visible print. The device is particularly adapted to the production of a latent image of a representation produced by the cathode ray tube of television or radar apparatus and immediately thereafter processing said frame to form a visible print, an image of which may be projected shortly thereafter onto a large viewing screen. Such a device is particularly adapted for use in apparatus of the type disclosed in the copending application of Edwin H. Land et al., Serial No. 244,822 filed on September 1, 1951, for Apparatus and Method of Indicating the Position and Motion of Phenomena in Space and the copending application of Norton T. Pierce et al., Serial No. 376,882, filed August 27, 1953, for Photographic Apparatus.

The photosensitive and second strips, being composed of different materials, tend to expand or shrink to different degrees during processing and particularly, for example, the photosensitive stri upon absorbing the liquid composition used in the process, tends to shrink to a greater degree than does the second strip. During the processing of relatively long strips of photosensitive material, this differential expansion or shrinkage may result in misalignment of superposed frames and areas or the building up of tension in one of the strips, resulting in a sudden movement or slippage of one of the strips with respect to the other and blurring or misregistration of the images. In addition, this differential shrinkage may result in variation in the distances between successive images. The necessity for compensating for the differential shrinkage or expansion of the strips becomes greater in apparatus of the type disclosed in the aforementioned applications wherein two or more successive images are projected and viewed simultaneously and wherein the uniform distance between adjacent images and accurate registration of the projected images is vital to the proper function of the apparatus.

It is accordingly one object of the present invention to provide, in photographic apparatus of the type wherein a photosensitive strip is processed in conjunction with a second strip, means for compensating for the above noted differential expansion or shrinkage of the two strips.

Another object of the present invention is to provide, in photographic apparatus, means for exposing and processing successive frames of a photosensitive strip by superposing each of said frames on an area of a second strip and spreading a layer of processing liquid between the strips, metering means for advancing one of said strips through said apparatus, and means utilizing the frictional forces between the superposed frame and area for advancing the other of said strips.

A further object of the present invention is to provide, in apparatus of the above type wherein said layer of processing comopsition is spread between a frame and an area by advancing said strips between a pair of pressure-applying members, metering means for positively advancing one of said strips through said apparatus and tensive means for predeterminedly controlling the forces resisting advancement of the other of said strips.

Still another object of the present invention is to provide apparatus of the above type comprising, in combination, means for intermittently advancing successive frames of a photosensitive strip into superposition with successive areas of a second strip, means for advancing said superposed frame and area between a pair of pressure-applying members, means for metering the length of one of said strips advanced between said pressure-applying members, means rendering the frictional forces between the superposed frame and area effective to advance the other of said strips with the length thereof being related to and compensating for the differential expansion or shrinkage of the two strips.

A still further object of the invention is to provide, in apparatus of the above type, the combination of means for intermittently advancing a metered length of one of said strips from its supply through said apparatus, means responsive to the advancement of said one of said strips for advancing the other of said strips through the apparatus, the length of said other of said strips advanced from its supply being related to and compensating for the differential expansion or shrinkage of the two strips, and means for so advancing said other of said strips from said apparatus into take-up means that the length thereof is equal to the length of said strip advanced from its supply into said appartus.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the apparatus possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein there is shown, diagrammatically in perspectve, apparatus embodying the present invention.

Referring now to the drawing, there is illustrated ap-' paratus embodying the present invention. Generally the apparatus includes: anexposing station 26 including lens and shutter means 22 and a guide means 24 for predeterminedly positioning afrarne of a photosensitive strip 26 in the focal plane of the lens; a processing station 28 through which associated portions of photosensitive strip 26 and a second strip 313 may be advanced in superposed relation with a layer of processing liquid therebetween; a

projection station 32 including lens 34-, a guide means 36 for predeterminedly positioning a section of strip 36 in the focal plane 'of the lens 34 and a source of illumination 33; means in the form of apair of sprockets 4d and 42 for metering and advancing successive image-receiving areas of second strip 30 through processing station 28' and projection station 32; means in the form of a pair of sprockets 4M and 46 for advancing successive frames of photosensitive strip 26 through exposing station' 29 and processing station 28; means including a tensive sprocket 48 for keeping successive sections of strip 26* taut and for compensating for the aforementioned differential expansion or shrinkage of the strips; and an electromechanical drive and control system.

The various components of the herein disclosed apparatus may be mounted on a-suitable support, the drive means being mounted on one side of said support and the strip-processing means on the other. means may be provided for enclosing the aparatus and particularly for shielding photosensitive strip 26, exposing station 2% and processing station 23 from environmental light and from light emitted from source of illumination 38.

Supplies (not shown) of photosensitive strip 26 and second strip 30 are provided in the form of rolls coiled within magazines or upon spools of conventional design mounted within the housing of the apparatus;- Mounted on second strip 30, which, in the embodiment illustrated, is adapted to receive or support a visible transfer image, are a plurality of rupturable containers each' carrying a quantity of liquid processing composition sufficient to produce a visible print in an image-receiving area of second strip 30 from a latent image in a frame of photosensitive strip 26. As shown, containers 50 are secured to second strip' 30 at substantially regularly spaced intervals from a location adjacent its leading end to its trailing end, the containers 50 being. so spaced that one container is associated with one image-receiving area.

Each container has a rupturable mouth which faces the trailing end of strip 30 and is adapted to eject its liquid content when subjected to opposed compressional forces.

Processing station 28 comprises a first pair of pressureapplying rollers 52 and 54 between which strips 26 and 30 are adapted to advance initially, and a second pair of rollers 56 and 53 between which the strips are adapted toadvance thereafter. Rollers 52 and 54 are adapted to superpo'se exposed frames of strip 26 upon associated areas of second strip 30 and to spread liquid processing composition therebetween. Rollers 56 and 58 cooperate with rollers 52- and' 54 to maintain associated frames and areas in superposition for predetermined processing periods during which latent images in'the frames are processed and positive prints are formed'in the areas. Rollers 56 and 58 enable uniform stripping of associated frames and'areas in-o'rder to permit images of the positive prints so formed to be displayed.

In order to enable observation of a positive print as quickly as possible after a latent image has been produced', exposing station and projection station 32 are positioned closely adjacent opposed sides of processing station 28 in order to permit a pair of immediately-adjoining frames of strip 26 to be respectively located in the exposing station and the processing station and to Suitable housing permit a pair of immediately adjoining areas of strip to be respectively located in the processing station and the projection station.

In accordance with the present invention, pairs of rollers 52 and 54 and 56 and 58 are so mounted as to exert compressional forces of precisely predetermined magnitude and direction so as to spread the processing liquid between associated portions of the strips in a thin layer of predetermined and uinform thickness. The rollers of each pair may be designed to cooperate both in guiding associated portions of the strips therebetween and in preventing processing composition between the strips from escaping therefrom. Rollers of the type suitable for use in the present invention, means for mounting the rollers Within the apparatus and resilient means for urging the rollers toward one another to apply opposed compressional forces to the strips are described in detail in the aforementioned application of Norton L. Pierce et al.

Further reference is made to the last-mentioned application for its disclosure of elements adapted for use and embodied in the present invention. These elements include guide means 24' for predeterminedly positioning successive portions of strip 26 in the focal plane of lens 22, guide means 36 for positioning successive portions of strip 30 transversely and prependicularly to its direction of advancement in the focal plane of lens 34, various sprockets for metering, advancing and te'nsioning the strips and guide and pad rolls for keeping the strips in mesh with the sprockets.

Metering means are provided for advancing successive sections of strip 30 from its supply through processing station 28 and projection station 32 to a take-up spool 60. This metering means includes a first sprocket 62 driven by means more fully to be described so as to rotate intermittently and advance strip 30 a distance substantially equal to the length of one image-receiving area from its supply into a take-up loop generally indicated at 64. Sprockets and 42 are rotated intermittently in synchronism so as to rapidly advance strip 39 the length of one area at a time through the processing and projection stations and thence to take-up spool whereon the strip is coiled. There are provided pad rolls 66; 68 and '70 adapted respectively to maintain strip 30 in engagement with sprockets 62, 4t) and 42'. These pad rolls may be mounted on'pivotable arms (not shown) to permit the threading of the strip through the apparatus. In addition, there are provided a guide roll 72 positioned adjacent projection station 32 and a spring-biased tension roll 74 mounted to engage strip 3% and keep the latter taut as'itis advanced along its path between synchronized sprockets 40 and 42. By virtue of the foregoing arrangement and construction, the predetermined over-all length of that section of strip 36- which extends from sprocket 40 to sprocket 42 is substantially maintained notwithstanding local expansion or contraction of the strip within the processing and projection'stations.

To advance photosensitive strip 26 through exposure station 20 and processing station 28 to a take-up spool 76 on which it is coiled and to compensate for the differential expansion or shrinkage of strips 26 and 30 during the advancement cycle thereof, there are provided a metering sprocket 44, a tensive sprocket 48 and a drive sprocket 46. Strip 26 is retained in engagement with sprockets 46; 48 and 44, respectively, by pad rolls 80, 82 and 84, 86 and 88; Strip 26 thus extends from its supply (not shown) around pad roll 84 into engagement with sprocket 44 where it is retained by pad rolls 84- and 86 suitably mounted on such means as pivoted arms to permit the threading of the strip between the pad rolls and the sprocket; Strip 26 extends from sprocket 44, around pad roll 82into engagement with tensive sprocket 48,-and thence through exposure station 20 and process irlg station 28 to drive sprocket 46, around pad roll 88,-

and into engagement with sprocket 44 from which it is metered into take-up spool 76. The various sprockets and paths of the photosensitive and second strips are illustrated as they would appear at the end of a stripadvancement cycle. The cycle is commenced at the actuation of a one-revolution clutch 90 which drives sprockets 44 and 62 and take-up spools 60 and 76 to advance photosensitive strip 26 and second strip 30 substantially the length of one frame and area thereof continuously during the cycle. Sprockets 40, 42 :and 46 are driven, substantially in synchronism with one another, by means such as a Geneva movement 92 for rapidly advancing strips 26 and 30 the length of substantially one frame and area at the beginning of a cycle. As illustrated, at the end of the cycle, strip 30 forms a loop 64, extending between sprockets 62 and 40, which permits the rapid advancement of the strips from the loop at the start of a cycle and strip 26 similarly extends into a loop generally indicated at 94 between sprocket 44 and sprocket 48. Immediately after rotation of sprockets 40, 42 and 46 is completed during the initial portion of a cycle, loops 64 and 94 would be substantially depleted, and another loop would be created in the portion of strip 26 extending between sprockets 46 and 44, this loop being entirely taken up by the rotation of sprocket 44 during the remainder of the cycle.

Strips 26 and 30, if composed of different materials, tend to expand or shrink to different degrees during processing. In the present case, for example, in processing station 28, strip 26 tends to shrink to a greater degree than does strip 30. It has been found that if equal lengths of strips 26 and 30 are metered through the apparatus and means are notprovided for compensating for this differential shrinkage, 'as the shrinkage continues, tension in that section of strip 26 extending through processing station 28 to sprocket 46 increases until it gradually overcomes the friction between portions of strips 26 and 30 within processing station 28 and suddenly causes strip 26 to slip forward with respect to strip 30. In addition, this differential shrinkage, if not compensated for, would result in the misalignment of frames of strip 26 with corresponding areas of strip 39 and varia tion in the distances between successive pairs of images formed in strip 30.

Means are provided for compensating for this differential shrinkage and, in the form shown, comprise means rendering the friction between strips 26 and 30 effective to advance strip 26 and thereby advance a greater length of strip 26 through the apparatus to compensate for the greater degree of shrinkage in said strip. The compensating means are further adapted to prevent any buildup of tension in strips 26 and 30 and to meter equal lengths of strip 26 from its supply into the apparatus and from the apparatus to take-up spool 76. In the form shown, this means comprises a sprocket 46 driven by Geneva movement 92 through a slip clutch 96 in synchronism with sprockets and 42. Tensive sprocket 48 is provided with a conventional friction brake or drag means (not shown) for resisting the movement of strip 26 and applying a tension thereto for keeping the strip taut. The tensive force exerted by sprocket 48 and the torque exerted by slip clutch 96 are so adjusted with respect to one another that the forces resisting the movement of strip 26 are slightly greater than the torsional force exerted by the slip clutch. Thus, slip clutch 96 will slip before the tensive force of sprocket 48 and the frictional forces on strip 26 resisting the movement of said strip can be overcome. The foregoing arrangement makes it necessary to impart an additional force to the strip to effect its movement, this force being the frictional forces between the portions of photosensitive strip 26 and second strip 30 within the processing station. In this manner the frictional forces between strips 26 and 30 are utilized to overcome a substantially equilibrium condition, in which strip 26 would normally remain motionless, to advance said strip in synchronism with strip 30. By virtue of this arrangement, the actual length of strip 26 advanced through the exposure and processing stations is equal to the metered length of strip 30 with which it is superposed.

within processing station 28, regardless of the degree of shrinkage in strip 26. Because the degree of shrinkage in strip 26 remains substantially uniform during the processing of each successive frame thereof, there is substantially no variation in the distance between the successive pairs of images in strip 30.

To meter equal lengths of strip 26 from its supply through exposure station 20 and processing station 28 and to take-up spool 76, there is provided sprocket 44 driven by single revolution clutch through a slip clutch 98. The path of strip 26 is so arranged that the strip engages sprocket 44 as it is withdrawn from its supply and :again as it comes from sprocket 46. By so driving sprocket 44 during each cycle that it tends to rotate slightly more than is necessary to advance strip 26 the length of one frame, slip clutch 98 is caused to slip when sprocket 44 has taken up the aforementioned loop, which is formed, during the initial portion of the cycle, in the section of strip 26 extending between sprockets 46 and 44. By virtue of this arrangement, the entire length of strip 26 advanced past sprocket 46 during each cycle is in turn advanced by sprocket 44 and the latter in turn meters an equal length of strip 26 from its supply. To compensate for the shrinkage in strip 26 as it is advanced in its path from and to sprocket 46, the initial length of strip 26 comprising loop 94 may be made longer than necessary, the added length being substantially equal to the total shrinkage to be anticipated in the entire strip to be processed.

As slip clutch 98 starts to slip, there may be imparted to the strip a sudden tug or jerk which, if transmitted through the strip, may be sufiicient to disturb the registration between associated portions of the two strips Within the processing station and movement of the section of strip 26 within the exposure station during exposure. To prevent any disruption of the processing and exposure, there is provided a clamping means 99 adapted to engage a portion of strip 26 between processing station 28 and sprocket 46. Suitable timing and drive means may be provided for causing the clamping means 99 to engage the strip after the motion of the Geneva movement is complete and before slip clutch 98 starts to slip and thereby prevent a suddent tug or tensive force from being transmitted through strip 26. Additional clamping means may also be provided in the exposing and projection stations associated with the guide means thereof to prevent movement of either of the strips during exposure, projection or processing.

The electromechanical drive and control system in cludes means such as an electric motor 100 which, when the apparatus is in operation, rotates continuously. A single revolution clutch 90 of conventional design is connected to motor 100 by gears 102 and is driven through one cycle by the motor, when electrical means opera- 'tively connected to the single revolution clutch receive an appropriate signal indicating shutter 22 has been tripped, to commence a strip-advancing and a processing cycle of the apparatus. Single revolution clutch 90 is operatively connected through drive sprocket 164, a drive chain 106 of conventional design, and drive sprocket 168 to a shaft 110 to which are secured drive sprocket 112 and Geneva movement 92. Drive sprocket 112 is in turn connected, through a drive chain 114 and a drive sprocket 116, to shaft 118, to which are secured a drive sprocket and sprocket 62. A drive chain 122, in engagement with drive sprocket 120, transmits the rotation thereof to: a drive sprocket 124 connected through a slip clutch 126 to take-up spool 60; a drive sprocket 123 connected through slip clutch 98 to metering sprocket 44; and a drive sprocket 130 connected through a slip clutch 132 to take-up spool 76.

By virtue of the foregoing arrangement, single revolution clutch 90 drives Geneva movement 92 and sprocket .7 q 62 directly, and drives meteringsprocket "44 and take-up spools 60 and 76 through their respective slip clutches. The .take up spools are connected through slip clutches so that *they maytake'up the entire lengths of the photosensitive and second strips advanced through the-apparatus regardless of the amount of said strips already coiled on the spools. Clamp 99 and-clamps incorporated into the guide means of the exposure and projection stations may be operated by suitable cams "(not shown) driven by single revolution clutch-90.

Geneva movement92drives, through gears 134, metering sprocket 40 "and drive sprocket 136. Metering sprocket 42 is driven by the'Genevamovemen't and connected thereto by a drive chain 138 and drive sprocket 140. Metering sprocket 46'is driven in synchronismwith sprockets 40 and 42 by a drive'sprocket "142 in engagementwith drive chain 138 and connected to sprocket 46 through a slip clutch96.

The components of the apparatus, once strip 26 has been threaded from sprocket '44"to sprocket "48 through exposing station 29 and processing station 28 to sprockets 46 and 44, and once strip 30 has been threaded from sprocket 62 to sprocket 4% through processing station '28 and projection station 32 to sprocket 42, operate in the following cycle. At a signal indicating that shutter 22 has been tripped, single revolution clutch 90 is actuated and Geneva movement 92 and drive sprocket 112 begin their rotation cycles with the following effect: clamp-99 and clamps associated with the processing and exposing stations are deactuated and the strips released for movement. At this point, sprockets 62 and '44 begin their rotational cycle which continues throughout .the stripadvancing cycle of the apparatus, and sprockets 40, 42 and 46, driven in synchronism by Geneva movement 92, begin their rotation cycle which is completed during the initial portion of the strip-advancing'cycle of the apparatus. As a result: a frame of'stn'p 26 is advanced into exposing station '20; the frame of strip 26, which has been within exposing station 20 together with an area-of strip 30, advances into processing station 28 in superposed relation with processing composition from a container 50 therebetween; and the area of strip 30, .which has been within processing station 28, advances therefrom and is stripped from the frame of strip 26 with which it has been in superposed relation.

After the termination of the rotational cycleof Geneva movement 92 and before termination of the rotation cycle of single revolution clutch *91), clamp "99 is reactuated and shutter 22 is tripped to expose the frame of strip 26, now positioned within exposing station 20, and one or more images in the portionof strip 30 within projection station '32 are displayed. Similar cycles occur at regular intervals or as desired whenever shutter 22 is tripped. In addition, shutter 22 may be held open for a predetermined exposure time 'to permit the exposure of a frame of strip 26 to one or more sweeps of a cathode ray tube associated with radar apparatus. Where the cycles occur at regular intervals, it is desirable that the processing composition employed be in such quantity and be so constituted as to perform its function when spread between strips 26 and 30 in a thin layer for a period of time which is predeterminedly related .to the intervals between the initiation of'successive cycles. For this purpose, suitable heating means, and particularly a conventional air heater, may be provided for raising the temperature of the apparatus, strips, and processing composition in order to reduce the length of :the predetermined processing period.

Since certain changes may be made .in the above apparatus without departingtfrom the scope-of the invention herein'involved, it is intended .that all matter containedin the above description or shown in the accompanying drawing shall be interpreted ;as illustrative and .not in a limiting sense.

What is claimed is:

1. In photographic apparatus 'for exposing successive frames of aphotosensitive strip and thereafter-processing said strip bysuperposing said frames on areas of a second strip and spreading a-layer of processing liquid beween associated frames andareas, the combination, with means forsuperposing said strips during processing, of a first and second sprocket for positively advancing portions of one of said strips from said first sprocket into superpositionwith the other of said strips to said second sprocket, and means cooperating with said other of said strips for rendering the frictional forces between associated portions of said superposed photosensitive and second strips effective to advance said other of said strips, said last-mentioned means including a tensive sprocket adapted to engage said-'otherof said'strips prior to superposition with saidone'of said strips, and a-drive sprocket adapted, thereafter, to-engage and advance said other of said strips, the forces exerted'on said other of said strips by said tensive sprocket'and said drive sprocket'beingin substantial equilibrium.

2. Photographic apparatus comprising, in combination, an exposing station-for producing latent images in successive frames of a photosensitive strip, a processing station for superposing said frames on successive areas of a second strip and for spreading processing composition between associated frames and areas, a first and a second sprocket for positively advancing portions of said second strip from said first sprocket through said processing station to said second sprocket, a tensive-sprocket-and a drive sprocket, said photosensitive strip extending from said tensive sprocket through said exposing station and said processing stationto said drive sprocket, said tensive sprocket being adapted to maintain said photosensitive strip taut, said drivesprocket being adapted to advance said photosensitive st-rip, the forces exerted on said photosensitive strip by said tensive and drive sprockets being in substantial'equilibrium, said processing station including means for superposing said strips during processing, the frictional forces between associated portions of said photosensitive and second strips within said processing station being sufiicient to alter said equilibrium condition and advance said photosensitive'strip.

3. Photographic apparatus comprising, in combination, an exposing stationfor producing'latent images in frames of a photosensitive strip, a processing station for superposing said "frames on successive areas of a second strip and for spreading processing composition between associated frames and areas, a first and a second sprocket for positively advancing metered lengths of said second strip from said first sprocket through said processing station to said second sprocket, a tensive sprocket and a drive sprocket, said photosensitive strip extending from said tensive sprocket through said exposing station and said processing station to said drive sprocket, said tensive sprocket being adapted to maintain said photosensitive strip taut, said drive sprocket being adapted to advance said photosensitive strip, the forces exerted on said photosensitive strip by said tensive and drive sprockets being in substantial equilibrium, said processing station including means for superposing said strips during processing, the frictional forces between associated portions of said photosensitive and second strips within said processing station being sulficient to alter said equilibrium condition and advance said photosensitive strip, the length of said photosensitive strip advanced being substantially equal to the metered length of said second strip regardless of the degree of variation in the length of each of said strips within said processing station.

4. Photographic apparatus comprising, in combination, an exposing station for producing latent images in frames of a photosensitive strip, 'a processing'station for superposing said frames on successive areas of a second strip and-for spreading processing-composition between associated frames and areas, a'firstand a-second sprocket for positively advancing metered lengths of said second strip from said first sprocket through said processing station to said second sprocket, a metering sprocket, a tensive sprocket and a drive sprocket, said photosensitive strip extending from said metering sprocket to said tensive sprocket, through said exposing station and said processing station to said drive sprocket, and thence to said metering sprocket, said processing station including means for superposing said strips during processing, said tensive sprocket being adapted to maintain said photosensitive strip taut and said drive sprocket being adapted to advance said photosensitive strip, the forces exerted on said photosensitive strip by said tensive and drive sprockets being in substantial equilibrium, the frictional forces between associated portions of said photosensitive strip and said second strip within said processing station being sufficient to alter said equilibrium condition and advance said photosensitive strip, the length of said photosensitive strip advanced by said frictional forces between the superposed strips being substantially equal to the metered length of said second strip regardless of the degree of variation in the length of each of said strips within said processing station, the length of said photosensitive strip advanced to said tensive sprocket being substantially equal to the length of said photosensitive strip advanced from said drive sprocket.

5. In photographic apparatus for processing successive exposed frames of a photosensitive strip, in combination, means for so superposing successive frames of said photosensitive strip with areas of a second strip as to generate frictional forces between said strips resisting movement of said strips relative to one another, said means comprising a pair of juxtaposed members disposed on opposite sides of said strips in engagement therewith for applying compressive pressure to the portions of said superposed strips located between said members, means for engaging one of said strips for advancing said one strip from said means for superposing said strips, and drag means in engagement with the other of said strips for exerting on said other strip a predetermined force resisting the advancement of said other strip between said juxtaposed members so as to maintain said other strip taut, the force exerted by said drag means tending to resist the advancement of said other strip being less than the frictional forces generated between said superposed strips and less than the force exerted on said one strip tending to advance said one strip whereby said frictional forces and said advancing forces exerted on said one strip are rendered effective to advance said other strip in superposition with said one strip, thereby maintaining substantial registration between associated frames and areas of said strips and a uniform spacing between successive areas regardless of variations in the relative lengths of said strips.

6. The photographic apparatus of claim wherein said drag means comprises a first mechanism in engagement with the other of said strips on one side of said pair of juxtaposed members for exerting on said other strip a predetermined force resisting the advancement of said other strip between said juxtaposed members, and a second mechanism located in engagement with said other strip on the opposite side of said juxtaposed members for exerting a force on said other strip tending to advance said other strip in superposition with said one strip between said juxtaposed members, the advancing force exerted by said second mechanism being predeterminedly less than the retarding force exerted by said first mechanism and the difference between said advancing and retarding forces being less than the frictional forces generated between said superposed strips.

7. In photographic apparatus for processing successive exposed frames of a photosensitive strip, in combination, means for so superposing successive frames of said photosensitive strip with areas of a second strip as to generate frictional forces between said strips resisting movement of said strips relative to one another, said means comprising a pair of juxtaposed members disposed on 0pposite sides of said strips in engagement therewith for applying compressive pressure to the portions of said superposed strips located between said members, means for engaging one of said strips on opposite sides of said pair of juxtaposed members for advancing said one strip, and drag means comprising a first mechanism in engagement with the other of said strips on one side of said pair of juxtaposed members for exerting on said other strip a predetermined force resisting the advancement of said other strip between said juxtaposed members so as to maintain said other strip taut and a second mechanism located in engagement with said other strip on the op posite side of said juxtaposed members for exerting a force on said other strip tending to advance said other strip in superposition with said one strip between said juxtaposed members, the advancing force exerted by said second mechanism being predeterminedly less than the retarding force exerted by said first mechanism and the difference between said retarding and advancing forces being less than the frictional forces generated between said superposed strips whereby said frictional forces are rendered effective to advance said other strip in superposition with said one strip, thereby maintaining substantial registration between associated frames and areas of said strips and a uniform spacing between successive areas regardless of variations in the relative lengths of said strips.

8. Photographic apparatus comprising, in combination, an exposing station for producing latent images in successive frames of a photosensitive strip, a processing station including means for superposing successive exposed frames of said photosensitive strip with areas of a second strip so as to generate frictional forces between said strips resisting movement of said strips relative to one another, said means comprising a pair of juxtaposed members disposed on opposite sides of said strips in engagement therewith for applying compressive pressure to the portions of said superposed strips located between said members, means for engaging said second strip for feeding said second strip from a supply through said processing station, and drag means in engagement with said photosensitive strip for exerting on said photosensitive strip a predetermined force resisting the advancement of said photosensitive strip through said exposure and processing stations so as to maintain said photosensitive strip taut, the retarding force exerted by said drag means on said photosensitive strip being less than the frictional forces generated between said superposed strips in said processing station whereby said frictional forces are rendered effective to advance said photosensitive strip in superposition with said second strip, thereby maintaining substantial registration between associated frames and areas of said strips and a uniform spacing between successive areas of said second strip regardless of variations in the relative lengths of said strips.

9. The photographic apparatus of claim 8 wherein said drag means comprises a first mechanism in engagement with said photosensitive strip on the side of said exposing station remote from said processing station for exerting on said photosensitive strip a predetermined force resisting the advancement of said photosensitive strip through said exposing and processing stations, and a second mechanism located in engagement with said photosensitive strip on the side of said processing station remote from said exposing station for exerting a force on said photosensitive strip tending to advance it through said exposing and processing stations, the advancing force exerted by said second mechanism being predeterminedly less than the retarding force exerted by said first mechanism and the difference between said advancing and retarding forces being less than the frictional forces generated between said superposed strips.

10. Photographic apparatus comprising, in combination, an exposing station for producing latent images in =11 successive frames of aphotosensitive strip, aprocessing station including means-i for superposing said frames of said photosensitive strip with successive areas of: asecond strip so as to cause" forces tobe generated between said strips resist-ingmovement-of said strips--relative to one-another, said 'meanscornprising apair ofjuxtaposed members disposedon-opposite sidesof said-strips in engagement therewith 'for' applying compressivepressure to the portions of said superposed stripslocate'd between said members within said--processing-*station,-meansfor engaging said second st'rip-on-opposite sides of said processingstation for advancing said second strip from its supply through said-processing station, and meansfor feeding said photosensitivestrip from its supply through said exposing and processing stations, thelast-named means comprising-a first mechanism-in engagement with said photosensitive --strip-between said-supply and said exposing station forexerting' on saidphotosensitive strip a predetermined force resisting the advancement of said photosensitive strip between said juxtaposed members so as to maintain said photosensitive strip -taut-within-said exposing and processing stations and a-second mechanism located in engagement with said photosensitive strip 'on the opposite side of said processing station for exerting a force-on said-photosensitive strip tending to advance it from said supply through said exposing station and into superposition with said second strip'between said juxtaposed members within said processing station, the advancing: force exerted by-said secondmechanism being predeterminedlyiess than the retarding force'exerted by said first mechanism and the ditferenee between-said retarding and advancing forces being less than said' froces generated between said superposed strips whereby said forces are rendered effective to'advance said photosensitive strip in superposition with said second -strip,= thereby. maintaining substantial registration betweenassociated frames and areas of said stripsand a uniform spacing between successive areas of saidsecond strip regardless. ofvariations in the relative lengths-of said strips.

'11. In photographic apparatus-of the character de-' scribed, means for advancing equal lengths of two strips through said apparatus regardless-ofthe degree of variation in the length ofeach of saidstrips occurring-during 1'2 advancement, said means comprising, in combination, means forengaging-and advancinga metered length of one-ofsaid-:strips'through said-apparatus, means for superposing the-otherof said strips with said one strip so that said one stripexerts frictional forces on said other strip tending to -advance the latter, the last-mentioned means-comprisingapair of juxtaposed members disposed on opposite sides of-saidstrips'in engagement therewith forapplying compressive pressure to the portions of said superposed strips locatedbetween said members, a sprocket in engagement with two spaced-apart portions of said other strip at two positions-on said sprocket, the path of said other strip through saidapparatus being so arranged that said sprocket engagessaid other strip on opposite sides of --said--juxtaposed members, said sprocket thereby 'meteringequal lengths ofsaid other strip into and -from superposition withsaid one strip between said juxtaposed members, -a"first mechanism in engagement with said otherstrip for exertingthereon a-predeterrnined force-resisting thewadvancementof said other strip'between said juxtaposedmembers so as to maintain said other striptaut, andasecond mechanismlocated in engagement with said other strip on the opposite side of said juxtaposedmembers forexerting a force on said other strip-tending to advance said other strip in superposition with said one strip between said juxtaposed members, the advancing force exerted-by said-second mechanism being predeterminedly' less than 'theretarding force exerted by said 'first' mechanismand the 'difierencebetween said retardingand advancing'forces'being less than said-frictionalforceswhereby'said frictional forces are rendered effective toadvance said other strip in superposition with said-one strip, Ithereby maintaining substantial registration between-associated-frames and areas of saidstrips and a uniform spacing-between successive areas regardless of variations in the relative lengths of-portions ofsaid strips.

Referenees Cited in-the'file of this patent UNITED STATES PATENTS 2,451,820 Garrett Oct. 19, 1948 

